I was copy-editing a report at work and came across the following sentence:
While sustainability in the transport sector was rated relatively high, the sustainability of the power sector was found to be weak.
The grammar nerd in me says this should be:
While sustainability in the financial and transport sector projects was rated relatively highly, the sustainability of the power sector was found to be weak.
Because after all, it feels more natural to say "The project was rated highly", rather than "The project was rated high."
But for some reason, I would feel more at ease saying "The project was rated relatively high." and not "The project was rated relatively highly.".
What is it about adding a "relatively" to this sentence that makes it different, when the fundamental syntax structure does not change? Adding one adverb in front of another doesn't automatically turn the former into an adjective does it? So why do I feel like it does here? Is "relatively" somehow unique relative to other adverbs? (see what I did there!)